#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>


 int g_val = 100;

int main()
{
    pid_t id = fork();
    if(id == 0)
    {
        int cnt = 5;
        //子进程
        while(1)
        {
            printf("i am child, pid : %d, ppid : %d, g_val : %d, &g_val : %p\n",getpid(),getppid(),g_val,&g_val);
            sleep(1);
            if(cnt) cnt--;
            else{
                g_val=200;
                printf("子进程change g_val : 100 -> 200\n");
            }
        }
    }

    else 
    {
        //父进程
        while(1)
        {
            printf("i am parent, pid : %d, ppid : %d, g_val : %d, &g_val : %p\n",getpid(),getppid(),g_val,&g_val);
            sleep(1);
        }
    }
            return 0;
}
